package cc.wsyw126.java.nowcoder.sword_offer;

import java.util.HashMap;
import java.util.Map;

/**
 * Created by Administrator on 2017/4/17.
 * 在一个长度为n的数组里的所有数字都在0到n-1的范围内。
 * 数组中某些数字是重复的，但不知道有几个数字是重复的。
 * 也不知道每个数字重复几次。请找出数组中任意一个重复的数字。
 * 例如，如果输入长度为7的数组{2,3,1,0,2,5,3}，那么对应的输出是重复的数字2或者3。
 */
public class Duplicate {
    // Parameters:
    //    numbers:     an array of integers
    //    length:      the length of array numbers
    //    duplication: (Output) the duplicated number in the array number,length of duplication array is 1,so using duplication[0] = ? in implementation;
    //                  Here duplication like pointor in C/C++, duplication[0] equal *duplication in C/C++
    //    这里要特别注意~返回任意重复的一个，赋值duplication[0]
    // Return value:       true if the input is valid, and there are some duplications in the array number
    //                     otherwise false
    public boolean duplicate(int numbers[], int length, int[] duplication) {
        boolean result = false;
        if (numbers == null || numbers.length == 0 || length == 0) return result;
        HashMap<Integer, Integer> integerIntegerHashMap = new HashMap<>();
        for (int i = 0; i < length; i++) {
            Integer integer = integerIntegerHashMap.get(numbers[i]);
            if (integer == null) {
                integer = 0;
            }
            integer++;
            integerIntegerHashMap.put(numbers[i], integer);
        }
        for (Map.Entry<Integer, Integer> integerIntegerEntry : integerIntegerHashMap.entrySet()) {
            if (integerIntegerEntry.getValue() > 1) {
                duplication[0] = integerIntegerEntry.getKey();
                result = true;
            }
        }
        return result;
    }

    public static void main(String[] args) {
        Duplicate duplicate = new Duplicate();
        int[] duplication = new int[1];
        boolean duplicate1 = duplicate.duplicate(new int[]{2, 1, 3, 1, 4}, 5, duplication);
        System.out.println("duplicate1 = " + duplicate1);

        System.out.println("Duplicate[0] = " + duplication[0]);
    }
}
